TRMM provides a closer look at hurricanes using a unique combination of passive and active microwave instruments designed to peer inside cloud systems and measure rainfall. TRMM allows scientists to study the combustion process in the hurricane engine and relate this process to intensification or weakening. Note: This is the standard definition version of the Hurricane Heat Engine - Cutaway animation MPEG. Animator: Susan Twardy (HTSI). Scientist: J. Marshall Shepherd (NASA/GSFC).